The Flintstones S04E18 - The Bedrock Hillbillies

The Hatrocks become depressed after they think the last of the Flintstones, whom they have been in a feud with for the last several hundred years, has died. They soon discover that one Flintstone family – Fred's – is still living. They send a fake will to get the Flintstones to come up and visit. When up at the Flintstone family cabin, the Hatrocks begin to feud with them to no end.